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Overview |
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Group |
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Quick Info
Windows NT
| Yes
| Win95
| Yes
| Win32s
| Yes
| Import Library
| user32.lib
| Header File
| winuser.h
| Unicode
| WinNT
| Platform Notes
| None
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GetClassLong
The GetClassLong function retrieves the specified 32-bit (long) value from the WNDCLASS structure associated with the specified window.
DWORD GetClassLong(
HWND hWnd,
| // handle of window
| int nIndex
| // offset of value to retrieve
| );
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Parameters
hWnd
Identifies the window and, indirectly, the class to which the window belongs.
nIndex
Specifies the 32-bit value to retrieve. To retrieve a 32-bit value from the
extra class memory, specify the positive, zero-based byte offset of the value to
be retrieved. Valid values are in the range zero through the number of bytes of
extra class memory, minus four; for example, if you specified 12 or more bytes
of extra class memory, a value of 8 would be an index to the third 32-bit
integer. To retrieve any other value from the WNDCLASS structure, specify one of the following values:
Value
| Action
| GCW_ATOM
| Retrieves an ATOM value that uniquely identifies the window class. This is the same atom that
the RegisterClass function returns.
| GCL_CBCLSEXTRA
| Retrieves the size, in bytes, of the extra memory associated with the class.
| GCL_CBWNDEXTRA
| Retrieves the size, in bytes, of the extra window memory associated with each
window in the class. For information on how to access this memory, see GetWindowLong and GetWindowWord .
| GCL_HBRBACKGROUND
| Retrieves the handle of the background brush associated with the class.
| GCL_HCURSOR
| Retrieves the handle of the cursor associated with the class.
| GCL_HICON
| Retrieves the handle of the icon associated with the class.
| GCL_HICONSM
| Retrieves the handle of the small icon associated with the class.
| GCL_HMODULE
| Retrieves the handle of the module that registered the class.
| GCL_MENUNAME
| Retrieves the address of the menu name string. The string identifies the menu
resource associated with the class.
| GCL_STYLE
| Retrieves the window-class style bits.
| GCL_WNDPROC
| Retrieves the address of the window procedure associated with the class.
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Return Values
If the function succeeds, the return value is the requested 32-bit value.
If the function fails, the return value is zero. To get extended error
information, call GetLastError.
Remarks
Reserve extra class memory by specifying a nonzero value in the cbClsExtra member of the WNDCLASS structure used with the RegisterClass function.
See Also
GetClassWord, GetWindowLong, GetWindowWord, RegisterClass, SetClassLong, SetClassWord, WNDCLASS
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